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[InstCombine] Folding loads through a phi node should merge the debug locations 

If all the operands to a phi node are a load, instcombine will try to pull
them through the phi node, combining them into a single load. When it does
this, the debug location of the new load should be the merged debug locations
of the phi node arguments.

Patch 5 of 8 for D26256.  Folding of a load operation.

Differential Revision: https://reviews.llvm.org/D26256

llvm-svn: 289688
This commit is contained in:
Robert Lougher 2016-12-14 19:02:14 +00:00
parent ff06759ffb
commit 373e36a410
2 changed files with 52 additions and 1 deletions
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2
llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -399,7 +399,7 @@ Instruction *InstCombiner::FoldPHIArgLoadIntoPHI(PHINode &PN) {
for (Value *IncValue : PN.incoming_values())
cast<LoadInst>(IncValue)->setVolatile(false);
NewLI->setDebugLoc(FirstLI->getDebugLoc());
NewLI->setDebugLoc(PHIArgMergedDebugLoc(PN));
return NewLI;
}

51
llvm/test/DebugInfo/Generic/instcombine-phi.ll
View File

@ -132,10 +132,53 @@ if.end: ; preds = %if.else, %if.then
ret i32* %r.0, !dbg !30
}
; Test folding of load. Generated from source:
; extern int *foo3(void);
; extern int *bar3(void);
;
; int load(int a) {
; int r;
; if(a)
; r = *foo3();
; else
; r = *bar3();
; return r;
; }
; CHECK: define i32 @load
; CHECK-LABEL: if.end:
; CHECK: %[[PHI:.*]] = phi i32* [ %call, %if.then ], [ %call1, %if.else ]
; CHECK: load i32, i32* %[[PHI]]
; CHECK-NOT: !dbg
; CHECK: ret i32
define i32 @load(i32 %a) !dbg !31 {
entry:
%tobool = icmp ne i32 %a, 0, !dbg !32
br i1 %tobool, label %if.then, label %if.else, !dbg !32
if.then: ; preds = %entry
%call = call i32* @foo3(), !dbg !33
%0 = load i32, i32* %call, align 4, !dbg !34
br label %if.end, !dbg !35
if.else: ; preds = %entry
%call1 = call i32* @bar3(), !dbg !36
%1 = load i32, i32* %call1, align 4, !dbg !37
br label %if.end
if.end: ; preds = %if.else, %if.then
%r.0 = phi i32 [ %0, %if.then ], [ %1, %if.else ]
ret i32 %r.0, !dbg !38
}
declare i32 @foo()
declare i32 @bar()
declare i64 @foo2()
declare i64 @bar2()
declare i32* @foo3()
declare i32* @bar3()
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
@ -170,3 +213,11 @@ declare i64 @bar2()
!28 = !DILocation(line: 30, column: 12, scope: !23)
!29 = !DILocation(line: 30, column: 10, scope: !23)
!30 = !DILocation(line: 31, column: 3, scope: !23)
!31 = distinct !DISubprogram(name: "load", scope: !1, file: !1, line: 34, type: !7, isLocal: false, isDefinition: true, scopeLine: 34, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!32 = !DILocation(line: 36, column: 6, scope: !31)
!33 = !DILocation(line: 37, column: 10, scope: !31)
!34 = !DILocation(line: 37, column: 9, scope: !31)
!35 = !DILocation(line: 37, column: 5, scope: !31)
!36 = !DILocation(line: 39, column: 10, scope: !31)
!37 = !DILocation(line: 39, column: 9, scope: !31)
!38 = !DILocation(line: 40, column: 3, scope: !31)